RU2094191C1 - Device for making multiple-layer soldered metal pipes - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: device for making multiple-layer soldered metal pipes 10 has roller arrangement A-E with several pairs of forming rollers 21, 22, 24, 25 for step plastic machining of metal strip passed through splined pipe RK to form initially non-soldered multiple layer body of pipe RK. Multiple-layer body of pipe RK is passed through axially spaced contact rollers 24, 25; 28,29 supplied with electric current and arranged in conductive zone of heating Z with zone of preliminarily heating ZV and zone of hardening ZY adjacent to preliminarily heating zone. Zone of cooling is located after hardening zone. Pair of contact rollers 28, 29 supplied with electric current is provided with independent drive to ensure higher speed of rotation as compared with speed of rotation of first pair of contact rollers 24, 25. Pipe feeding device F arranged in direction of flow behind cooling section can be adjusted to meet pipe feeding speed in area of second pair of contact rollers 28,29. EFFECT: enlarged operating capabilities. 12 cl, 4 dwg

Description

 The invention relates to a device for the manufacture of brazed metal pipes according to the restrictive part of paragraph 1 of the claims.

 Such a device is described in patent EP N 0036968 B1.

 In the case of the known device according to patent EP N 0036968 B1, the entire conductive heating zone, which carries out continuous heating to the soldering temperature of a multilayer, in particular a two-layer pipe body moving at a pipe feed speed, is limited to two elements that are supplied with electric current. The first element, powered by electric current, and located in the direction opposite to the flow direction relative to the pipe feed direction, consists of a contact shoe fixed parallel to the longitudinal axis of the pipe body in its axial direction. Opposite it, in the direction of flow, there is a thermal or soldering chamber filled with shielding gas in which the soldering zone is located. In this soldering chamber there is also a second element, powered by an electric current, which consists of a rotating rotating contact pair driven by a pipe feed movement, the contact rollers of which have circumferential grooves with correspondingly partially annular cross-section along their outer circumference (calibration) to ensure good electrical contact. Contact rollers provide at the end of the glow zone, in which the solder, in particular copper solder, evaporates, along with its electrical contact functions, simultaneously fixing the pipe body before this body stabilizes after cooling and the hardened brazed multilayer steel pipe, in particular into a two-layer pipe.

 In the case of the device known from patent EP0 036968, it is essential that the contact shoe located in the direction opposite to the flow of movement moves together with the first element supplied with electric current, thereby providing control of the length of the glow zone. In this case, both elements supplied with electric current are connected to an alternating current source with transformed low voltage.

 EPO 036968 also describes in detail a roller device for the stepwise plastic conversion of a flat strip-like metal strip passed through a splined pipe to obtain an initially solderless two-layer pipe body. For this, a tube-rolling unit with separate rolls, which consist respectively of a pair of forming rolls, is provided. This pair of forming rollers, which is located in the direction of flow relative to the pipe feed direction, which grips the rolled multilayer but not soldered pipe body, also covers a calibration mandrel, the so-called float, in the same plane of the cross section. This float forms a symmetric gauge body of revolution with broken transitions, which, expanding in the direction of flow, is mounted on the free end of the traction rod, which has a smaller diameter compared to the float. The end of the traction rod, which is held motionless in space, is passed in the direction against the flow movement with respect to the float from the splined zone of the pipe casing to the outside and is fastened there.

 Another device for the manufacture of brazed multilayer metal pipes is described in patent DE 886945. In this patent, from three pairs of contact rollers located in the direction opposite to the flow movement, they move independently from each other in the axial direction (compare figures 3, 4, 7, 24, 27 , 8, 9, 23, 22, 21). From the patent DE 886945 it is impossible, however, to obtain more detailed information regarding the tube rolling device. Similarly, in the case of a device of the type described above (EPO 036968 B1), a reduced transformed single-phase AC voltage is applied to the elements supplied with electric current according to patent DE 886945 (compare Figure 2, position 6).

 The device according to patent EPO 036968 has proven itself in practice, as far as it was initially possible with such a device, to implement in a simple manner a continuous soldering process, despite the tolerant dimensions with the pipe body not soldered.

 The device according to the patent EPO 036968 is considered the best if necessary, since the known device does not allow more to obtain an increase in labor productivity. Based on the above-described known device according to EPO 036968 B1, the present invention is based on the task of thus changing the known device, while maintaining its simple structure, and further improving it so that it would significantly increase labor productivity.

 In accordance with the invention, this problem is solved due to the fact that a pair of forming rollers, which covers a non-soldered multilayer pipe body and also a float, forms a first contact roller pair located at the same time in the opposite direction of the flow along with the first element supplied by an electric current representing the beginning of the heating zone that the second pair of contact rollers located in the direction of flow relative to the first pair of contact rollers, which forms the second element, pit supplied by electric current, and at the same time the end of the heating zone, is provided with its own drive and has a higher rotation speed than the first pair of contact rollers, and that the feed rate of the pipe with the help of a feeding device is set depending on the pipe feed speed existing in the region of the second pair of contact rollers .

 The device in accordance with the invention can significantly increase the productivity that is possible when using a known device of the specified type (EP0 036968).

 This is possible primarily due to the fact that a pair of forming rollers, which covers the solderless multilayer pipe body and also the float, forms the first pair of contact rollers simultaneously located in the opposite direction of the flow with the first element supplied with electric current, which is a heating zone. This inventive feature makes it possible, first of all, to obtain a simple design, since the tube rolling unit located in the subsequent direction of the flow movement, along with the plastic shape-changing function it performs, receives the additional function of an element supplied with electric current. The peculiarity lies in the fact that in this invention it was determined that the normal pressure acting from the calibrated forming rollers through the multilayer pipe body to the float directed radially inward is simultaneously used as contact pressure to supply electric energy to the multilayer pipe body. Thanks to this first element, which is supplied with electric current, this results in a prerequisite for optimal electrical contact, as a result of which electrical energy can be supplied over the entire cross-sectional surface of a multilayer, in particular a two-layer pipe casing, into this casing, which is a decisive prerequisite for increasing labor productivity and obtaining reliable work results.

 The use of a tube rolling unit located further in the direction of the flow direction as the first element supplied with electric current is further based on the fact that a heated multilayer pipe is an extremely unstable formation, which should, if possible, have no mechanical contacts, thereby avoiding deformation and thereby marriages in the wound pipe body (wrong soldering, wrong size). Also, from this point of view, it is extremely effective to use the existing tube rolling unit as an element supplied with electric current, since the sealed multilayer pipe body does not undergo changes in its position in the radial direction in the annular gap between the float and both forming rollers.

 Another significant inventive feature is that the second contact roller pair located in the direction of flow relative to the first contact roller pair, which forms the second contact, is supplied with electric current, and at the same time the end of the heating zone is provided with its own drive and has a higher rotation speed than first contact roller pair. The term "own drive" should be understood, for example, a drive that is diverted from the gearbox, and in particular, in contrast to conventional contact rollers known to the present in the art, which rotated as a result of the movement of the pipe feed.

 The high rotation speed of the second contact roller pair makes it possible, in accordance with the present invention, to take into account thermal changes in the length that occur when the pipe body is heated, in order to avoid sagging of the pipe body between the elements supplied with electric current due to the appearance of harmful lateral displacements.

 Another inventive feature is also effective, according to which, the feed rate of the device feeding the pipe is set depending on the feed rate of the pipe existing in the area of the second contact roller pair.

 From the patent DE 886945 (cf. page 4, lines 44 54), it is known that the friction forces of the contact rollers can act on the pipe surface due to the somewhat faster rotation of the pair of electric contact rollers than this corresponds to the feed rate of the pipe body. This type of drive for contact rollers, although it may be applicable for certain cases of its application, but in the case of other examples of its application as a result of friction between the contact rollers and the pipe surface, harmful vibrations cannot be avoided. For a larger number of possible applications, it has established itself as an expedient embodiment in accordance with the present invention, according to which a pair of contact rollers and pipe feeding devices rigidly capture the outer surface of the pipe, at least basically rigidly, thus avoiding harmful vibrations , to ensure that vibration-free passage of the pipe through the heating zone.

 In another embodiment, the invention provides for an equal distance between the first contact roller pair and the second contact roller pair, the middle contact roller pair with the middle element, fed by electric current, which has its own drive, and the pre-heating zone is located between the first and middle element, fed by electric current , and the glow zone is located between the middle and the second element, powered by electric current. Three spaced-apart contact roller pairs are known mainly from DE 886945 (compare Figures 1 and 2). The advantage of this design consists mainly in a more advantageous electric power distributed over three contact roller pairs, and in the ability to optimize the preheating zone by changing the distance between the first and middle contact roller pairs. Such a change in distance is required in the present invention, usually only during the first installation or the first installation of the device. Technological change of any distance in order to take into account, for example, size fluctuations due to defects in the pipe, is not required in the device in accordance with the present invention as opposed to known devices (EPO 036968 B1). This is confirmed by other inventive features, in accordance with which all contact roller pairs remain stationary relative to the longitudinal axis of the pipe body.

 From DE 886945, elements are known to which an alternating supply current is supplied, and at the same time, the preheating zone and the glow zone are switched on in parallel. In contrast, to obtain higher labor productivity, it turns out to be more advantageous in another embodiment of the invention to supply the elements to which electric current is supplied with direct current and at the same time include the preheating zone in the glow zone in parallel. Moreover, in accordance with additional features of the present invention, in order to control the supplied electric power to the elements supplied with electric current, both the electric voltage and the strength of the electric current are changed.

 In this case, a variant of constructive use in accordance with the present invention has proved itself to be particularly advantageous for regulating the initial phase and also for adjusting technological states, according to which, for supplying elements to which an electric current of controlled electric power is supplied, a three-phase current transformer is connected to each phase at the input, a thyristor device that controls power in that a rectifying rectifier is connected at the output of each individual phase the device and that the three phases of direct current for powering the elements to which the electric current is supplied are connected together to two connecting terminals. An advantage of the electric power control circuit described above in accordance with the present invention is that axial movement of a particular roller pair can be completely dispensed with, in particular when the preheating zone is set only once between the first contact roller pair and the middle contact roller pair for a certain type of pipes, and this happens during the first installation of the device.

 The power control depending on the size of the pipe and the feed rate of the pipe can then be carried out in accordance with the present invention exclusively through a thyristor device that controls the power at the input of the transformer.

 From the brochure "Conductive heating of metals", published in 1989 by the Rhine-Westphalian Electricity Accentgensellschaft (see pages 15 and 16 there in conjunction with Figure 37), it is known that, in conjunction with incandescent wire, they provide for the regulation of electric power at the output of current amplification through thyristors, as well as a series circuit for switching on a three-phase current transformer and an injector. However, unlike the invention, in the case of incandescent wire belonging to a different field of technology, various electric powers are supplied due to different voltages. For the invention, on the contrary, it is essential that the three phases of the direct current supplying power to the elements to which the current is supplied, for both pipe sections connected in parallel (preheating zone and glow zone) are connected together to two terminals.

 The following features of the invention arise from the additional claims.

 In FIG. 1 shows in axonometric projection a partially two-layer steel pipe brazed with copper; in FIG. 2 part of the device for the manufacture of brazed multilayer steel pipes, located in the direction against the flow relative to the direction of the pipe feed or the flow; in FIG. 3 part of a device for manufacturing brazed multilayer steel pipes, located in the direction of flow, in a schematic representation; in FIG. 4 power supply circuit.

 In FIG. 1, reference numeral 10 denotes a two-layer steel pipe brazed with copper. Both layers of the steel strip are indicated by 11 and the copper layers (shown by a thick line) are indicated by 12.

 The starting material for a two-layer pipe (Fig. 1), brazed copper, is steel strip 11 galvanically coated on both sides with a copper layer 12, which forms a coil 13 (Fig. 2).

 The tape material in sections 14 and 15 has a beveled area on each of them to obtain an evenly rounded end of the pipe (Fig. 1).

The device (Fig. 2, 3) operates as follows:
Two traction rollers 16 pull the copper-coated steel strip 11, 12 from the rotating coil 13 (not shown), and therefore move the copper-coated tape 11, 12 in the feed direction or in the direction of flow X.

 In pipe rolling aggregates A and B, the steel strip coated with a layer of copper 11, 12 is then converted, cold plastic, into a splined pipe with a slot 17 expanding upward. Through mandrel 17, mandrel 19 fixed at its end 18 at point 20 penetrates into the inside of the splined pipe and extends in the direction of supply X beyond the tube rolling units C, D and E.

 Thus, in the direction of flow X, a pipe body RK (Fig. 1) arises behind the piping unit E, with the difference that it has not yet been soldered.

 The forming rollers of the tube rolling units A-D, although they are different with respect to their rollers, are indicated in general by the reference number 21 and their rotation direction by the letter U.

 The mandrel 19 has at its free end an actual mandrel part, namely a calibration mandrel, the so-called float 22. The float 22 is a symmetrical body of revolution with a longitudinal convex contour, passing with overcoming elastic resistance in the X direction.

 The mandrel 19 also has a traction rod 23, to the free end, which extends in the direction of flow of the stream, to which the float 22 is attached. The float 22 has a larger outer diameter than the traction rod 23.

 Both forming rollers 24, 25 (Fig. 2, 3) pairs of forming rollers 24, 25 located further downstream of the tube rolling unit E form a gauge K, which in its cross section is an approximately semicircular shaped groove around the outer circumference of the forming rollers 24, 25 .

 A device for producing a two-layer steel pipe 10 by brazed copper is indicated by the letter J.

 Device J has a first electric current supply element P1, a second electric current supply element P2, and a middle electric current supply element PM.

 The first element P1, powered by electric current, is formed by a pair of forming rollers 24, 25 of the tube rolling unit E, which, in addition to the function of plastic change of shape, also performs the function of electric contact rollers. The forming rollers 24, 25 press against each other a two-layer pipe body (mainly in accordance with Fig. 1) to the float 22 in a round shape so that at this point optimum electrical contact is obtained between the forming rollers 24, 25 and the inner two-layer pipe body RK, leaning on a float 22.

 Next to the first element P1, which is supplied with electric current, but remote from it in the direction of flow in the X direction, there is a middle element PM, supplied with electric current, with two contact rollers 26, 27. These contact rollers 26, 27, similarly consisting of the corresponding metal, mainly steel, taking into account the thermal elongation of the soldering zone, have a semicircular caliber, basically identical to the forming rollers 24, 25. The contact rollers 26, 27 are in close contact with the semicircular surface of the housing and pipes RK.

 Similarly, as the contact rollers 26, 27 are made structurally contact rollers 28, 29, which are the second element P2, powered by electric current.

 Contact rollers 26, 27; 28, 29 are located in a thermal or soldering chamber 47, which consists of two separate soldering chambers 30 and a sealed connecting pipe 46 located between them. The internal space of the soldering chamber 47 contains a protective gas atmosphere, in particular a mixture of hydrogen and nitrogen, to prevent oxidation pipe body RK. A special design of the soldering chamber 47, i.e. its division into three separate parts 30, 46, 30 can significantly reduce the amount of protective gas.

 The inputs and outputs of the individual soldering chambers 30 are respectively connecting sleeves 31 of the corresponding material.

 In the direction of flow, adjacent to the soldering chamber 47 is an elongated cooling chamber 32, in which cooling medium flows, in particular water flows, and which is only partially reduced in length to simplify the drawing.

 In the direction of flow, behind the cooling chamber 32, there is a pipe feeding device F, which in the case of the shown embodiment has two steel rollers 33, 34, which are identical to the contact rollers 26, 27 or 28, 29, whose caliber K is tight and strong capture the round surface of the finished two-layer steel pipe 10 and serves to the coil device.

 Elements PI and PM, powered by electric current, form a pre-heating zone ZV between themselves (Fig. 3).

The incandescent zone ZJ is located between the middle element PM, supplied by electric current, and the second element P2, supplied by electric current. When this is located inside the soldering chamber 30 actually glowing section of the filament, on which the pipe body is heated to a temperature of about 1150 ^o C and soldering occurs.

 Forming rollers 24, 25 (as well as all other forming rollers 21 of A-D pipe rolling units), as well as contact roller pairs 26, 27 and 28, 29 and a pair of feed rollers 33, 34 have their own drives.

 The pipe zones ZV and ZJ, which are under the influence of an electric current, are connected to each other in parallel (Fig. 4).

 The device J is supplied with electric current from a three-phase current network with phases R, S, T. There is a voltage of 380 V between the phases.

 Each phase has a power control at the input, which is carried out by means of respectively two antiparallel connected thyristors or thyristor groups 35. The three phases R, S, T, which regulate power, are connected to the primary winding 1 of a three-phase current transformer 36 having a triangle connection to the secondary winding of which II, for each phase, a device for rectifying the current 37, 38 is connected. All have, respectively, a device for rectifying the current 37, 38 direct voltage power controllers, with offset relative to each other is connected in phases to two connected terminals 39, 40. These connection terminals 39, 40 then provide a pulsating, but thanks to the presence of three phases, a sufficiently smoothed DC voltage with an average voltage of approximately 50 V, which is preferably the maximum voltage.

 Connected terminals 39, 40 are connected in parallel live sections of the pipe ZV and ZJ. The entire heating zone is indicated by the reference number Z. Although not shown in the drawing, both rollers 24, 25, or 26, 27 or 28, 29 of the electric current elements P1, PM and P2 are connected to the connection terminals 39, 40, respectively. Roller devices 24, 25, as well as 28, 29 have grounding at point 31.

 The forming rollers 24, 25 located further downstream in the flow direction of the tube rolling unit E have their own drives, for example, through drive shafts of the drive of the rolling mill. The forming rollers 24, 25 are connected, rotating as a result of this, rigidly between each other. The forming roller 25 can, for example, drive an electric tachometer 42, which is connected to the distribution box 43 using a multi-core electric cable 44. Pairs of contact rollers 26, 27; 28, 29, as well as a pair of feed rollers 33, 34 of the pipe feeding device F are connected respectively to an electric motor 45 driving them. An electric tachometer 42 is likewise located on each motor shaft. Both the motors 45 and the electric tachometers 42 are connected via a multi-core cable 44 to a control box 43, so that a known servo control is obtained.

 During operation of device J, the number of revolutions of the pair of forming rollers 24, 25 is sent through the electric tachometer 42 as the main base value to the computing device of the switchboard 43. This computing device compares the pairs of contact rollers 26, 27 and 28 received from the remaining electric tachometers. 29, as well as a pair of feed rollers 33, 34, electrical signals between each other and then regulates the speed of individual motors 45 by comparing the actual set value so that all The rollers 26, 27, as well as 28, 29, arranged successively in the direction of flow, on the pipe body RK or steel rollers 33, 34 on the two-layer pipe 10 rotate without slipping.

 The contact rollers 26, 27, as well as 28, 29 and the feed rollers 33, 34 are interconnected according to a single movement pattern (not shown) using an appropriate drive, for example, using a timing belt drive.

 It is very important to mention that the regulation of the electric power supplied to the elements P1, PM and P2, supplied with electric current, as well as to start the device J, and to maintain a uniform technological mode is carried out only with the help of adjustable transistor devices 35 connected to transformer inlet 36.

 The control of the rotational speeds of the pairs of contact rollers 26, 27, as well as 28, 29 and the pairs of feed rollers 33, 34 is electrically blocked through the control box 43 (which is known), so that individual adjustment of the rotational speed of any pair of rollers 26, 27 can be performed; 28, 29 and 33, 34 only with the help of a separate inclusion.

Claims (12)

 1. A device for the manufacture of brazed multilayer metal pipes containing several pairs of forming rollers, a calibration mandrel mounted on the free end of the traction rod, contact rollers connected to a power source, means for cooling the pipe and means for feeding the pipe, characterized in that it is provided an additional pair of contact rollers with a drive for their rotation, located in front of the main pair of contact rollers connected to a power source and electrically connected to the latter along the process process, a pair of forming rollers that are electrically connected to the main pair of contact rollers.  2. The device according to claim 1, characterized in that the last pair of forming rollers, the main and additional pairs of contact rollers are located at equal distances from each other.  3. The device according to claim 1 or 2, characterized in that all pairs of rollers are mounted motionless relative to the longitudinal axis of the device.  4. The device according to claim 3, characterized in that the additional pair of contact rollers is configured to provide a higher rotational speed than the rotational speed of the last pair of forming rollers and to provide a lower rotational speed of the main pair of contact rollers.  5. The device according to any one of claims 1 to 4, characterized in that the last pair of forming rollers and the main pair of contact rollers are equipped with drives for their rotation.  6. The device according to any one of paragraphs.1 to 5, characterized in that all pairs of rollers and a device for feeding the pipe are installed with the possibility of ensuring a tight, without slipping, fit to the outer surface of the pipe being manufactured.  7. The device according to any one of paragraphs.1 to 6, characterized in that the drives for rotating a pair of rollers and means for supplying a pipe are electrically connected.  8. The device according to any one of paragraphs.3 to 7, characterized in that the last pair of forming rollers and the main pair of contact rollers are connected to one pole of the power source, and an additional pair of contact rollers is connected to the second pole of the power source.  9. The device according to claim 8, characterized in that it is equipped with a means for regulating the electric power supplied to the forming and contact rollers by changing the voltage and current.  10. The device according to p. 9, characterized in that it contains an electric circuit consisting of a transformer, thyristor devices and rectifying devices, wherein each phrase the phase of the transformer is connected at the input to the thyristor device and at the output to the rectifying device and three phases of a DC source connected together to two terminals connected to all pairs of rollers.  11. The device according to claim 10, characterized in that each thyristor device contains two thyristors connected in opposite directions.  12. The device according to claim 11, characterized in that the transformer is connected according to a triangle circuit.

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